离子文件下载不起作用

Question

我在为壁纸构建离子应用程序。

在应用程序中，显示存储在www/assets/img中的图像。我在下面创建了2个按钮，用于将显示的图像下载并检索到移动设备内存。

当我点击下载按钮时，会显示一个对话框，说“下载成功！Pug.jpg已成功下载到：filepath”。但是当我检查手机内存时，没有这样的文件存在。还有，当我点击“Retrieve “按钮，它显示的对话框说”文件检索成功Pug.jpg成功地从检索：。文件路径“”即使文件不存在在手机内存

这是home.ts代码

import {Component} from '@angular/core'; 
import {NavController, Platform, AlertController} from 'ionic-angular'; 
import {Transfer, TransferObject} from '@ionic-native/transfer'; 
import {File} from '@ionic-native/file'; 

declare var cordova: any; 

@Component({ 
    selector: 'page-home', 
    templateUrl: 'home.html', 
    providers: [Transfer, TransferObject, File] 
}) 

export class HomePage { 

    storageDirectory: string = ''; 

    constructor(public navCtrl: NavController, public platform: Platform, private transfer: Transfer, private file: File, public alertCtrl: AlertController) { 
    this.platform.ready().then(() => { 
     // make sure this is on a device, not an emulation (e.g. chrome tools device mode) 
     if(!this.platform.is('cordova')) { 
     return false; 
     } 

     if (this.platform.is('ios')) { 
     this.storageDirectory = cordova.file.documentsDirectory; 
     } 
     else if(this.platform.is('android')) { 
     this.storageDirectory = cordova.file.dataDirectory; 
     } 
     else { 
     // exit otherwise, but you could add further types here e.g. Windows 
     return false; 
     } 
    }); 
    } 

    downloadImage(image) { 

    this.platform.ready().then(() => { 

     const fileTransfer: TransferObject = this.transfer.create(); 

     const imageLocation = `${cordova.file.applicationDirectory}www/assets/img/${image}`; 

     fileTransfer.download(imageLocation, this.storageDirectory + image).then((entry) => { 

     const alertSuccess = this.alertCtrl.create({ 
      title: `Download Succeeded!`, 
      subTitle: `${image} was successfully downloaded to: ${entry.toURL()}`, 
      buttons: ['Ok'] 
     }); 

     alertSuccess.present(); 

     }, (error) => { 

     const alertFailure = this.alertCtrl.create({ 
      title: `Download Failed!`, 
      subTitle: `${image} was not successfully downloaded. Error code: ${error.code}`, 
      buttons: ['Ok'] 
     }); 

     alertFailure.present(); 

     }); 

    }); 

    } 

    retrieveImage(image) { 

    this.file.checkFile(this.storageDirectory, image) 
     .then(() => { 

     const alertSuccess = this.alertCtrl.create({ 
      title: `File retrieval Succeeded!`, 
      subTitle: `${image} was successfully retrieved from: ${this.storageDirectory}`, 
      buttons: ['Ok'] 
     }); 

     return alertSuccess.present(); 

     }) 
     .catch((err) => { 

     const alertFailure = this.alertCtrl.create({ 
      title: `File retrieval Failed!`, 
      subTitle: `${image} was not successfully retrieved. Error Code: ${err.code}`, 
      buttons: ['Ok'] 
     }); 

     return alertFailure.present(); 

     }); 
    } 

} 

这是home.html代码

<ion-header> 
    <ion-navbar> 
    <ion-title> 
     File Transfer Example 
    </ion-title> 
    </ion-navbar> 
</ion-header> 

<ion-content padding> 
    <ion-card> 
    <ion-card-header> 
     Ionic 3 File Transfer Example 
    </ion-card-header> 
    <ion-card-content> 
     <img src="assets/img/pug.jpg" alt="Cute Pug"> 
     <button ion-button (click)="downloadImage('pug.jpg')" color="secondary">Download image</button> 
     <button ion-button (click)="retrieveImage('pug.jpg')" color="secondary">Retrieve downloaded image</button> 
    </ion-card-content> 
    </ion-card> 
</ion-content> 

我建立在此基础上Github code example

其实我是想离子应用先在内部存储器中的文件夹（命名的文件夹的应用程序），并把there.So用户可以在该文件夹中访问文件的所有图像这种离子的应用程序。例如，如果应用程序名称是“Appsample”，则所有图像应位于内部存储器中的Appsample文件夹中。

我该如何发展以上目的？

谢谢。

Answer 1

我刚刚张贴的答案，几乎同样的问题，请参见：

Download not working using filetransfer plugin。

这里的主要问题是，您使用以下目录保存文件：

else if(this.platform.is('android')) { 
     this.storageDirectory = cordova.file.dataDirectory; 
} 

正如科尔多瓦文档（https://cordova.apache.org/docs/en/latest/reference/cordova-plugin-file/#where-to-store-files）说：“cordova.file.dataDirectory”是持久的和私人使用内部存储器在应用程序的沙箱中存储数据。

使用cordova.file.externalDataDirectory以符合您的目的。然后该文件应放置在某处：“file：/// storage/emulated/0/Android/data/subdomain.domainname.toplevdomain/files/...”。

在Android上，外部存储目录始终存在。如果设备没有物理卡，Android会模拟它。